鱼雷锚安装特性的数值分析

发布时间：2018-02-01 10:18

本文关键词： 拖曳阻力拖曳系数鱼雷锚长径比冲击速度贯入深度强度参数　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：采用紧绷式锚泊系统固定深海钻井平台的关键问题是鱼雷锚在不同海床中的贯入深度与所能提供的抗拔承载力。本文采用数值方法分析了鱼雷锚在水中的运动特性及贯入海床土体中的特性,通过大量计算,得出以下结论；鱼雷锚在水中运动所受的拖曳力会随着运动速度的增加而增加,鱼雷锚的拖曳系数并非定值,拖曳系数随着运动速度的增加而减小,拖曳系数的总体变化不是很大,所以在一定的速度变化范围内拖曳系数可以近似当作定值。在长径比相同的情况下,通常鱼雷锚锚头越具有流线型,其拖曳系数较小,反之较大。LS-DYNA的CEL算法可以模拟鱼雷锚在水中运动的过程,其结果与理论计算方法的结果很接近。鱼雷锚贯入海床土体的过程为快速过程,总历时极短(秒级),贯入过程可分为加速与减速两个阶段,其中减速阶段历时较长。贯入阻力随贯入深度增加而增大至峰值,当速度接近零时,贯入阻力出现陡降,最终贯入阻力(静阻力)与鱼雷锚重力平衡。随着冲击速度增加,贯入深度相应增大,且两者具有较好的线性关系。当冲击速度不变时,贯入深度随L/D增加而减小。海床土体强度参数c、φ的变化对鱼雷锚的贯入过程具有重要影响,随强度参数增加,贯入深度相应减小。
[Abstract]:The key problem of using tight mooring system to fix deep-sea drilling platform is the penetration depth of torpedo anchor in different seabed and its uplift bearing capacity. In this paper, the kinematic characteristics of torpedo anchor in water are analyzed by numerical method. Properties and characteristics of the soil penetrating into the seabed. Through a large number of calculations, the following conclusions are drawn; The drag force of the torpedo anchor in the water will increase with the increase of the moving speed. The drag coefficient of the torpedo anchor is not constant, and the drag coefficient decreases with the increase of the moving speed. The overall variation of drag coefficient is not very large, so the drag coefficient can be regarded as a constant value in a certain range of velocity changes. In the case of the same aspect ratio, the more streamlined the torpedo anchor head is. The drag coefficient is small, whereas the CEL algorithm of .LS-DYNA can simulate the moving process of torpedo anchor in water. The result is very close to that of the theoretical calculation method. The process of torpedo anchor penetration into the seabed soil is a fast process, and the total duration is very short (second order). The penetration process can be divided into two stages: acceleration and deceleration. The penetration resistance increases to the peak with the increase of penetration depth. When the velocity is close to 00:00, the penetration resistance drops sharply. The final penetration resistance (static resistance) is balanced with the gravity of torpedo anchor. With the increase of impact velocity, the penetration depth increases correspondingly, and there is a good linear relationship between the penetration resistance and the torpedo anchor gravity, and when the impact velocity is constant, the penetration depth increases accordingly. The depth of penetration decreases with the increase of L / D. the variation of soil strength parameters c and 蠁 has an important effect on the penetration process of torpedo anchors, and the penetration depth decreases with the increase of strength parameters.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU476;U653.2

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